Immune responses, both cellular and humoral, of the autochthonous host to the presence of tumor cells, and presumably to particular tumor-associated antigens, have been described in experimental animal systems and in humans. Data has been acquired which shows that immunoglobulin, and possibly anti-tumor cell antibody, is present in tumor tissues and bound to tumor cells. In this laboratory, immunoglobulin has been shown to be associated with squamous carcinoma cells of tumors of the head and neck regions. The objectives of continuing studies are to characterize the tumor-bound immunoglobulin and cancer sera-derived immunoglobulin with specificities to probable tumor-associated antigens of the carcinoma cells, as to their binding by various immunochemical techniques. It has also been shown in many laboratories that the A,B,H antigenic determinants are not present on squamous carcinoma cells whereas benign tumor and normal epithelial cells exhibit those determinants on their cell surfaces. Therefore, a major objective of this proposal is to describe the distributions of certain blood group precursor sequences (the I,i and T and Tn antigenic determinants) in tumor tissues as compared to marginal and normal epithelial tissues to determine if particular precursor determinants may be expressed as tumor-associated markers. We have shown that cancer patient sera adds back immunoglobulin to tumor sections from which the immunoglobulin has been removed by low pH buffer washes. We intend to study the reactivities of the tumor-bound and cancer sera immunoglobulins to such washed tissues as regards specificities and cross-reactivities to individual and different tumor tissue sections. We will attempt to identify certain possible tumor-associated antigens to which tumor-bound immunoglobulin may be forming antibody-antigen complexes, and to ascertain whether antibody to the blood group precursor determinants constitutes a portion of the tumor-associated immunoglobulin.